Final answer:
The arrangement of the sides of the DNA molecule is best described as antiparallel, meaning the two strands run in opposite directions, contributing to the double helix structure.
Step-by-step explanation:
The best description of the arrangement of the sides of the DNA molecule is antiparallel.
This means that one strand of DNA runs in the 5' to 3' direction and the other strand runs in the 3' to 5' direction, creating a structure where the two strands are parallel but oriented in opposite directions.
Additionally, the DNA molecule is a double helix, where two strands of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base, are twisted around each other.
The nitrogenous bases adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G) through hydrogen bonds, forming the steps of the twisted staircase-like structure.